Vapor heater



5 w w. SCHROEDTER 2,867,415

VAPOR HEATER Filed June 17, 1955 '2 Sheets-Sheet 1 Willburt W.Schroedter Fig. I.

ATTOR NE 1" 2,867,415 VAPoR HEATER Willburt W; Schroedter, New York, N.Y., assignor to Combustion Engineering, Inc., New York, N. Y., a

corporation of Delaware Application June 17, 1955, Serial No. 516,261.

1 Claim. (Cl. 257-241) This invention relates to vapor heaters of thetubular panel type and has particular relation to such heatersemployedwith vapor generators that have furnaces into which fuel is introducedand burned with the combustion gases thus generated traversing the vaporheater and with the vapor heater being located so as to receive luminousradiation from the'burning fuel within this furnace.

In accordance with this invention there is provided a vapor heatercomprised of a number of tubular panels positioned within a gas passleading from the furnace of a vapor generator. These panels are spacedacross the width of the gas pass and have their median planes inparallel relation with the gas flow with the panels being located sothat their upstream edge is subjected to radiant heat from the furnace.Each of the panels is preferably atent made up' of a plurality of tubespositioned next to one another and formed into a panel by beingsinuously bent and internested one Within the other. The tubes of theseveral panels of'the vapor heater are interconnected so that the vaporflows serially through these panels in passing through the vapor heater.In order to prevent the tubes that are nearest to the upstream edge ofthe panels from being overheated the panels are interconnected in such amanner that thesame steam does not flow through the tubes nearest theupstream edgeof eachof the panels but instead the steam that flowsthrough the tubes adjacent the upstream edge of one panel is directedthrough tubes that are more remote from the upstream edge of anotherpanel.

It is an object of this invention to provide an improved vapor heater ofthe tubular panel type. 1

'Other and further objects of the invention will become apparent tothose skilled in the art as the description proceeds.

With the aforementioned objects in view, the invention comprises anarrangement, construction and combination of the elements of theinventive organization in such a manner as to attain the results desiredas hereinafter more particularly set forth in the following detaileddescription of an illustrative embodiment, said embodiment being shownby the accompanying drawing wherein:

Fig. 1 is a vertical sectional view showing a portion of the furnace ofa vapor generator and a vapor heater constructed in accordance with thepresent invention associated with this furnace.

Fig. 2 is a transverse sectional view taken along line 2-2 of Fig. 1 andshowing the panels of the vapor heater interconnected and spaced acrossthe gas pass leading from the furnace.

Fig. 3 is a vertical sectional View taken along line '33 of Fig. 1 andlikewise shows the tubular panels spaced ?atented Jan. .6, 1959 sentedtube sections being taken along line 55 of Figs. 1 and 3.

Referring now to the drawing, wherein likereference characters are usedthroughout to designate like elements there is shown a furnace 10 whichhas its Walls lined with steam or vapor generating'tubes 12 in theconventional manner and which is fired with a suitable fuel throughburners 14 which may be located at the corners'of the furnace and be ofthe well known vertically tiltable type. This fuel is burned withinfurnace 10 with the combustion gases that are generated passing upwardlyfro-m the furnace into the gas pass 16 that extends upwardly from thefurnace and may be said to form an extension of the furnace with thegases leaving gas'pass 16 through duct or passage 18.

Extending downwardly into gas pass 15 is the steam or vapor heater 20which may take the form of a superheater or reheater for reheating thesteam or vapor generated in tubes 14 or may be any other type of vaporheater. This vapor heater 20 is composed of tubular panels 22, 24, 26and 28 that are position-ed in side-byside spaced relation across thewidth of the gas pass with each panel being of such size that it extendsalmost the entire distance across the depth of gas pass 16.

In the illustrative organization shown each of the panels of the vaporheater 20 is made up of six tubes that have been'designated 30, 32, 34,36, 38 and at as indicated, with the axes of each of these tubes lyingin the median plane of the panel and with the tubes being sinuously bentand internested as shown.

The vapor to be heated enters the tubes of panel 22 from inlet header42, which is connected to the initial run or leg of the sinuously formedtubes of this panel, and is conveyed serially through panels 22, 24, 26and 28, respectively, leaving panel 28 through the final run or leg ofthe tubes of this panel and entering outlet header 44 to which thesetubes are connected. In order for the steam to serially flow throughthese several panels the tubes of adjacent panels are interconnected bymeans of combustion gases flowing upward through gas pass 16 give upheat to the panels of vapor heater 2% by means of convection heatexchange as well as non-luminous radiant heat exchange. In addition thepanels also re, ceive luminous radiant heat from the burning mass offuel within furnace 10 with this heat being extremely intense and withthe intensity of this heat received by the tubes in each paneldecreasing with the distance of the tubes from the upstream edge of theparticular panel, i. e., the further the tube is displaced from theleading edge of the panel the less of this luminous radiant heat itreceives. The intensity of this luminous radiant heat is such that ofthe total heat absorbed by all of the tubes in each panel-that absorbedby the upstream tube, i. e., the tube extending along the upstream edgeof the panel, will be much greater than that absorbed by any other tubeand with the percentage of heat absorbed by each tube decreasing as itsdistance from the upstream edge of the panel increases. This Will becomeevident by a consideration of Fig. 5 which is a graphic representationof the total heat absorbed by the vapor in passing through panel 22 withthe shaded area under curve 48 representing the total heat absorbed andwith the portionof the shaded area to the right of each represented tubeindicating the portion of this total that is absorbed by the vapor inthe respective tube. It is thus evident that the vapor in the tubesnearest the upstream edge of the panel (tube 30 being disposed along theupstream edge) absorbs considerably more heat than those remote from theupstream edge resulting in a substantially higher tube metal temperaturein the tubes nearest this upstream edge.

It will thus be readily apparent that if tubes 30 through 40 of onepanel were connected to the coresponding tubes 30 through 40 of the nextsucceeding panel the stream that flows through the tube extending alongthe upstream edge of one panel would also flow through the tubeextending along the upstream edge of the succeeding panel, and likewisethe steam flowing through the second tube from the upstream edge of onepanel would flow through the corresponding tube of the next succeedingpanel and so on. This would cause the tubes near the upstream edge ofpanels near the end of the vapor heater, i. e., the exit end relative tovapor flow, to either become prohibitively hot or if not prohibitivelyhot would result in the necessitating of fabricating these tubes ofextremely expensive heat resisting metal to Withstand the hightemperature that would be encountered. 1

In order to avoid overheating the tubes near the upstream edge of thepanels and to more nearly attain a uni-' form metal temperature of thetubes in the panels the tubes in different panels are interconnected ina manner so that the vapor that passes through the tubes of the upstreamedge of one panel will pass through tubes more remote from the upstreamedge of other panels of the vapor heater with this being accomplished inthe illustra-- tive organization by connecting tubes 30, 32, 34 of onepanel with tubes 36, 38, 40 of the next succeeding panel throughconnecting conduits 46. Thus the vapor that flows through tubes 30, 32and 34 of one panel, which are the tubes nearest the upstream edge ofeach of the panels; is directed through tubes 36, 38 and 40,respectively, of the nearest succeeding panel with these latter tubesbeing more remote from the upstream edge of the panel thereby attaininga more equal distribution of the heat absorbed by the steam in the tubesand accordingly of the tube metal temperatures.

It is to be understood, however, that while this inter- 1 connection ofthe tubes of different panels will accomplish applicants purpose ofproviding more uniform metal temperature of the tubes in the panelsother and different interconnecting arrangements may be employed foraccomplishing this purpose with the essential requirement being that thepattern of steam flow paths in the panels making up the vapor heater bevaried'sufliciently so that the same steam does not flow through thetubes that are nearest the upstream edge of each of the panels. t

It will be evident that with the novel vapor heater of the presentinvention the vapor in flowing from inlet header 42 to outlet header 44traverses gas pass 16 both across its depth as well as across its Widthso that any variation in gas flow or gas temperature in any directionacross the gas pass will be averaged out so as to have no substantialeffect upon the vapor temperature and at the same time the tubes nearestto the upstream edge of the of the several panels are protected frombecoming overheated or extremely hot in comparison with the other'tubesin the panels.

While I have illustrated and described a preferred embodiment of mynovel organization it is to be understood that such is merelyillustrative and not restrictive and that variations and modificationsmay be made therein without departing from the spirit and scope of theinvention. I therefore do not wish to be limited to the precise detailsset forth but desire to avail myself of 'such changes as fall within thepurview of my invention.

What I claim is: i

A vapor heater comprising a pluralityof vertical panels disposed inside-by-side relation within a gas passageway opening directly out of afurnace and through which combustion gases from said furnace aredirected, the median planes of the panels being inspaced relation acrossthe width of the passageway and generally parallel with the gas How, thepanels being disposed so that the upstream edge thereof is subjected tointense radiant heat with the portions of the panels more remote fromthis upstream edge receiving progressively less radiant heat, saidpanels being comprised of numerous continuous tubes interconnectedbetween inlet and outlet headers. with a portion of each of the tubesbeing disposed within the plane of each panel and thereby making up aportion ofthe panel whereby the vapor flows serially through the several.panels, these tube portions being sinuously bent and internested toform the panels, in passing from one panel to another the group of tubesdisposed nearest the upstream edge of a panel and comprising generallyhalf of the tubes that make up the panel being crossed with relation tothe remainder of tubes with each of these groups of tubes beingcrossedin a body so that the relative location of the tubes within eachgroup remains unchanged while the relative location of the groups ischarged with this crossing of tubes in this manner positioning alternateof these groups of tubes nearest'the upstream edge in adjacent panels.

References Cited in the file of this patent

